On the topic of small rooms:
I owned an A/V operation and enjoyed offering "creative solutions." After one-too-many customers stating: "My room’s not big enough for Home Theater", we decided to take a little action.
I ordered a 30" x 30" British phone booth (replica) and installed a 7.1 system in it. The design goal was when someone stated the familiar: "My room’s not big enough for Home Theater", we’d be ready with: "Is it bigger than 30 by 30 inches?" We built a custom baffle in the ceiling, took the "guts" out of B&W mini monitors, raised the floor 4", and installed a pair of low-profile JLAudio subs in the floor. Amplification was outboard and we used a vintage pay phone as a keypad to control basic functions. A 26" Sharp monitor completed the system. It played VERY loud and, yes, the bass POUNDED!! We calculated that it was the equiviant of having 4 kilowatts of power and 150" screen in an "average sized" room. It was alot of fun. Especially the day when a couple of female college students crammed themselves in it together, and we had to "assist" getting them out.
I also think it’s worth mentioning that we were very involved in competition car audio. We won a national title -- back in the day when sound quality mattered. In the car environment we were producing (and, measuring) ruler-flat response down to 32hz, and 130db+ SPLs were routine in vehicles exiting our shop. I guess we didn’t know it couldn’t be done.